This is usually because the video outputs are often connected only to the discrete gpu, while the laptop screen is only connected to the integrated GPU, meaning you have to use both if you want monitors. On desktop, NVIDIA mostly works if you stick to X11 and deal with their proprietary driver. However, the hybrid graphics switching presents a lot of problems. Some ThinkPads actually can behave like desktops and disable the iGPU entirely, since they have a mux that can connect the dGPU to the laptop screen directly, without using any render offload shenanigans, though at a great cost of battery life.